Isolation and identification of some steroidal glycosides of Furcraea selloa.

The antischistosomal impact of different extracts of the leaves of Furcraea selloa C. Koch (Family Agavaceae) were screened against adult Schistosoma mansoni worms in vitro using well established culture media. The methanol extract of the plant showed the highest activity as S. mansoni worms recorded 100% mortality at 50 microg/ml after 24 h (EC50 = 29.78 and 29.41 microg/ml for female and male worm respectively). Owing to the high potency of the crude butanolic extract (100% mortality at 20 microg/ ml; EC50 = 10.42 and 8.94 microg/ml for female and male worm respectively) obtained from the methanolic extract, it was submitted to chromatographic separation and isolation using silica gel and Sephadex columns as well as preparative thin layer chromatography. Three steroidal glycosides (saponins) (I-III) were isolated and their structures were elucidated using some spectroscopic and chemical methods. The structure of the three compounds was formulated as 6-O-beta-glucopyranosyl-(1-->4)-beta-D-glucopyranoside chlorogenin (I), 3-O-beta-D-glucopyranosyl-(1-->4)-beta-D-glucopyranoside crestagenin (II) and 3-O-beta-D-glucopyranosyl-(1-->3)-beta-D-glucopyranosyl-(1-->3)-beta-D-xylopyranoside gloriogenin (III). Only compound III at 5 micro/ml led to 100% mortality of the S. mansoni (EC50 = 2.25 and 1.91 microg/ml for female and male worm respectively) whereas compounds I and II did not show any activity up to 50 microg/ml.